The purpose of this proposal is to undertake an in-depth analysis of data (collected with support of NICHHD 1976-78 on 120 intact families) to build a causal model to identify how family structure and process variables influence intellectual development of four-year-old children. The family variables under study are family size, birth order (ordinal position), birth interval (spacing ), and parental belief systems and childrearing practices. The research question is to determine the relative contribution each of these familial variables make to intellectual functioning of children, as well as the impact of the children's intellectual functioning on parental decisions regarding changes in family size as well as belief systems and practices. The methods employed include parent-interviews and observations, and administration of tasks to the children assessing intellectual and social problem soliving capabilities. The rationale underlying this research is the need to specify in detail the interplay of the above factors as they affect intellectual capabilities of young children. Moreover, we need to know more about how parental childrearing beliefs and practices interact with increasing parental experience associated with family size and spacing of children. The parent-child relationship is viewed in this context as interactional in which parent and child are both teacher and learner. Data collected should enable us to provide specific information regarding the relationships among: (1) family structure variables, (2) parental childrearing beliefs, (3) parental childrearing practices, and (4) the intellectual competencies of young children. This information will be applicable to parent education programming, cognitive developmental theory, and policy regarding family planning.